#include <iostream>
using namespace std;

const int N = 5010;

int n,m;

int a[N][N];
int f[N][N];

int main(){
	cin >> n >> m;
	while(n--){
		int x,y,v;
		cin >> x >> y >> v;
		a[++x][++y] += v;
	}
	n = 5001;
	for(int i = 1;i <= n;i++){
		for(int j = 1;j <= n;j++){
			f[i][j] = f[i - 1][j] + f[i][j - 1] - f[i - 1][j - 1] + a[i][j];
		}
	}
	int ret = 0;
	
	m = min(n,m);
	
	for(int x2 = m;x2 <= n;x2++){
		for(int y2 = m;y2 <= n;y2++){
			int x1 = x2 - m + 1,y1 = y2 - m + 1;
			ret = max(ret,f[x2][y2] - f[x1 - 1][y2] - f[x2][y1 - 1] + f[x1 - 1][y1 - 1]);
		}
	}
	
	cout << ret << endl;
	return 0;
}
